For items such as this, in the listing you should state that unless noted otherwise in a message to seller that you will use a default finish or Seller's Choice option OR set your listing up using the variations tabs that way the buyer must make a choice before purchasing. This way you aren't hung up trying to finish and ship and item.
It is possible that the buyer didn't read the full listing and doesn't know to have made a choice. I say give it 3 business days and if no response, finish the item like the first photo of your listing and send it on its way and when you do, send a message to your buyer stating that due to lack of communication as to how buyer preferred finishing of item it has been completed like the initial image on the listing.